Sentinel Range

Wilchem Sentinel is a range of Ethylenediaminetetraacetic acid (EDTA) chelates. EDTA forms sexadentate chelates – they form six bonds to the nutrient to form a “chelate ring”. As can be seen in the diagram below showing the octahedral structure of EDTA chelating a metal ion. The chelate ring is stronger than a single ionic bond and protects the nutrient and maintains it in solution. EDTA chelates protect the nutrient from interaction with other crop protection products making it the most compatible product on the market. The synthetic EDTA molecule does not provide any additional nutritional benefit, it purely acts as a stable transporter of the micronutrients in solution.

EDTA Structure

Diagram of the octahedral structure of zinc EDTA forming a hexadentate chelate.

Foliar micronutrient applications can enter the plant two ways. Via the stoma which is used by the plant for respiration or by direct absorption through the leaf cuticle. EDTA chelates cannot be absorbed directly through the cell membrane. The micronutrient must first be uncoupled from the EDTA molecule either in the rhizosphere (soil applications) or epidermis or palisade cells (foliar applications). It can then be absorbed through the cell exchange process.